Effects of heat-treatment on microstructures and mechanical properties of WO3 particle and Al18B4O33 whisker hybrid reinforced Al matrix composites by squeeze casting

In this paper, WO3p and Al18B4O33w hybrid reinforced aluminum matrix composites were fabricated by squeeze casting. Heat-treatment of the composites was carried out at 500 °C for different times. Gibbs free energy calculation indicated that the reaction of WO3 with Al was spontaneous. DTA result showed that the reaction of WO3 with Al took place at 396 °C and 487 °C. XRD results showed that the interfacial reaction occurred after heat-treatment at 500 °C for 5 h and 10 h and the reaction products were WO2.90 and WO2.83, which resulted in the formation of micro-voids at the interface between particle and matrix and led to mechanical properties of the composites decreasing. However, mechanical properties of the composites heat-treated for 10 h did not decrease obviously compared with that of heat-treated for 5 h. The reason may be that the produced aluminum oxide film covered the WO3p and retarded progress of the chemical reaction.